#region Copyright & License

//
// Copyright 2001-2005 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

#endregion

using log4net.Core;
using log4net.Util;

namespace log4net.Repository.Hierarchy {
  /// <summary>
  /// The <see cref="RootLogger" /> sits at the root of the logger hierarchy tree. 
  /// </summary>
  /// <remarks>
  /// <para>
  /// The <see cref="RootLogger" /> is a regular <see cref="Logger" /> except 
  /// that it provides several guarantees.
  /// </para>
  /// <para>
  /// First, it cannot be assigned a <c>null</c>
  /// level. Second, since the root logger cannot have a parent, the
  /// <see cref="EffectiveLevel"/> property always returns the value of the
  /// level field without walking the hierarchy.
  /// </para>
  /// </remarks>
  /// <author>Nicko Cadell</author>
  /// <author>Gert Driesen</author>
  public class RootLogger : Logger {
    #region Public Instance Constructors

    /// <summary>
    /// Construct a <see cref="RootLogger"/>
    /// </summary>
    /// <param name="level">The level to assign to the root logger.</param>
    /// <remarks>
    /// <para>
    /// Initializes a new instance of the <see cref="RootLogger" /> class with
    /// the specified logging level.
    /// </para>
    /// <para>
    /// The root logger names itself as "root". However, the root
    /// logger cannot be retrieved by name.
    /// </para>
    /// </remarks>
    public RootLogger(Level level) : base("root") {
      Level = level;
    }

    #endregion Public Instance Constructors

    #region Override implementation of Logger

    /// <summary>
    /// Gets the assigned level value without walking the logger hierarchy.
    /// </summary>
    /// <value>The assigned level value without walking the logger hierarchy.</value>
    /// <remarks>
    /// <para>
    /// Because the root logger cannot have a parent and its level
    /// must not be <c>null</c> this property just returns the
    /// value of <see cref="Logger.Level"/>.
    /// </para>
    /// </remarks>
    public override Level EffectiveLevel {
      get { return base.Level; }
    }

    /// <summary>
    /// Gets or sets the assigned <see cref="Level"/> for the root logger.  
    /// </summary>
    /// <value>
    /// The <see cref="Level"/> of the root logger.
    /// </value>
    /// <remarks>
    /// <para>
    /// Setting the level of the root logger to a <c>null</c> reference
    /// may have catastrophic results. We prevent this here.
    /// </para>
    /// </remarks>
    public override Level Level {
      get { return base.Level; }
      set {
        if (value == null)
          LogLog.Error("RootLogger: You have tried to set a null level to root.", new LogException());
        else
          base.Level = value;
      }
    }

    #endregion Override implementation of Logger
  }
}